OBD II and engine overheat (vehicle, air bag, buying, driver)
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I'm looking for a used car and want to avoid one that has been overheated. Does anyone know if the P0217 overtemp code stays in memory or will it be erased after codes are cleared?
Thanks for your help.
Basically any code is cleared when told to be cleared as well as if power is lost for, basically any amount of time.
Does seem like something they could do.. Put flash memory in there, write to it, and keep a 'history' of trouble codes that survives battery disconnects. Only real issue might be setting date/time.. But, we've got auto-setting clocks that cost less than $15.
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Quote:
Originally Posted by Labonte18
Basically any code is cleared when told to be cleared as well as if power is lost for, basically any amount of time.
Does seem like something they could do.. Put flash memory in there, write to it, and keep a 'history' of trouble codes that survives battery disconnects. Only real issue might be setting date/time.. But, we've got auto-setting clocks that cost less than $15.
There are some ECUs that store data outside of the OBDII codes, I've heard of more than one BMW M3 warranty claim being denied due to the driver selecting the wrong gear on a downshift and over-revving the engine resulting in KERBLAMO!
There are also some ECUs (I don't think they're mandatory, yet) that store data like speed and G-forces (similar to an aircraft's 'black box') that can be read and used to determine such things as whether an air bag didn't deploy because the forces were below the trigger threshold or not. I believe that info can only be accessed by the manufacturer.
There are some ECUs that store data outside of the OBDII codes, I've heard of more than one BMW M3 warranty claim being denied due to the driver selecting the wrong gear on a downshift and over-revving the engine resulting in KERBLAMO!
There are also some ECUs (I don't think they're mandatory, yet) that store data like speed and G-forces (similar to an aircraft's 'black box') that can be read and used to determine such things as whether an air bag didn't deploy because the forces were below the trigger threshold or not. I believe that info can only be accessed by the manufacturer.
Isn't the 'black box' separate from the ECU until OBDIII?
I'm no expert on this, but I had thought the 'black box' functionality was built into OBDIII, and any vehicles that currently have it were separate devices that accessed OBDII data, but weren't 'built in'
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Quote:
Originally Posted by Labonte18
Isn't the 'black box' separate from the ECU until OBDIII?
I'm no expert on this, but I had thought the 'black box' functionality was built into OBDIII, and any vehicles that currently have it were separate devices that accessed OBDII data, but weren't 'built in'
Oh, I'm no expert either. AFAIK, things like an over-rev are stored in the ECU, other things (speed, Gs, etc.) may well be stored in a separate box. I occasionally see someone who's involved with that type of thing, next time I see him I'll ask. I've just heard of some law suits where defective airbags were claimed and the recorded data showed the forces involved were below the trigger threshold. I haven't really kept up with OBDIII and a quick search leads me to believe there's still a lot up in the air with it.
I think the answer to this question for most of the general car-buying population is no. There is no way to tell if the car has been overheated. Once the OBD2 codes are cleared, the average OBD2 scanner will not be able to tell.
Special tools are not something most people have access to.
To be quite honest, I've worked on a few cars that have overheated, and they never generated that particular code.
Depends on the the vehicle but, clearing the Data Trouble Codes erases all of the OBD-II system's memory settings.
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